Type bar impact control



June 12, 1956 w. J. LONG 2,750,022

TYPE BAR IMPACT CONTROL Filed Oct. 20, 1954 s Sheets-Sheet 1 T FIG. 1

RUBBER BINDING ST-RIP 1F- INVENTOR.

"WILLIAM J. LONG w m M4 5 June 12, 1956 w. J. LONG TYPE BAR IMPACTCONTROL 5 Sheets-Sheet 2 Filed Oct. 20, 1954 INVENTOR. WILL] M J. LONGk) (wMr June 12, 1956 w. J. LONG 2,750,022

TYPE BAR IMPACT CONTROL Filed Oct. 20, 1954 3 Sheets-Sheet s FIG. 6

LIJLLI E2 0 INVENTOR. 8 WILLIAM J LONG mum;

Patented June 12, 1956 TYPE BAR IMPACT CONTROL William J. Long,Poughkeepsie, N. Y., assignor to International Business MachinesCorporation, New York, N. Y., a corporation of New York Applicationctober'20, 1954, Serial No. 463,432

7 Claims. (Cl. 19717) This invention relates to typewriting mechanismsand more particularly to an improved upper and lower case selection andimpression control for a typewriter.

The typewriter art has always been faced with the problem of producingequal color density for upper and lower case characters, sincegenerally, the upper case character has a larger area (and hence for anygiven force, a lesser pressure per square inch of printing area) thanthe lower case character carried by the same type bar. As a result ofthis difference in pressure, the color density of the upper casecharacter usually will be less than that of the lower case character forany one impression control setting. Industry, however, demands that alltype characters be of uniform color density, and accordingly, it is afirst object of this invention to provide an improved upper and lowercase impression control for a typewriter.

Another uniform printing problem is presented by the typing conditions.For example, by the ribbon; that is, whether it be cloth or carbon whenused in conjunction with various types of printing paper, or if noribbon at all is used, as in stencil work. More specifically, it isgenerally understood in the typewriter art, that a range of imprintpressure-sometimes called group control--.-is required for each set ofprinting conditions in order to govern the required color density oruniform depth of paper plate penetration for each character stenciled.

For any one set of typing conditions, the group control may be setselectively at maximum imprint pressure for dark typing or deeppenetration, 'or at some position in the group control range giving alesser imprint pressure for a relatively lighter typing or penetration.However, the range of imprint pressure or group control for one set oftyping conditions may be entirely diiferent from the group control rangerequired for another set of printing conditions. A specific example of"condition change (a term hereinafter used in this specification todenote a complete change of typing conditions requiring a differentrange of group control) may be found in the light range of imprintpressure required for stenciling paper plates (as used for example, induplicating processes) wherein a delicate uniform paper penetration isrequired for a single sheet, in contrast with the heavyrange ofimpression control required when either fabric or carbon ribbon is usedin combination with conventional letter writing paper wherein four ormore carbon copies may be required.

Because of this great variance in range of group control, it has beennecessary, in order to provide the degree of perfection that industrydemands, to equip some business ofiices with two typewriters; eachadjusted to handle respectively one class of printing conditions.

In order to avoid this expensive machine duplication, it is an object ofthis invention to provide an improved typewriter impression controlwhich is operable to handle two entirely different classes of printingconditions, or condition changes.

It is a further object of this invention to provide an improvedimpression control mechanism wherein, an upper and a lower case controlis provided respectively for each type bar so that it may operateproperly for tw sets of condition change."

Other objects of the invention will be pointed out in the followingdescription and claims and illustrated in the accompanying drawings,which disclose, by way of example, the principle of the invention andthe best mode which has been contemplated of applying that principle.

In the.drawings:

Fig. 1 is a side elevation of one type bar drive mechanism positionedfor operation with an improved impression control mechanism.

Fig. 2 is a top view of the improved impression control mechanism. I

Fig. 3 is a side elevation of the impression control mechanism shownoperatively connected to a basket shift mechanism.

Fig. 4 is a side elevation taken through plane 44 of Fig. 2, while Fig.5 is a front elevation taken through plane 5-5 of Fig. 4.

Fig. 6 is a perspective view of the improved impression control bar usedin conjunction with my improved control mechanism.

Briefly, this invention relates to an improved impression controlmechanism wherein a plurality of rows of adjustable stops arecircumferentially spaced about the periphselectively to co-act with atype bar drive mechanism to regulate its degree of impression control.

As an introduction to the subject matter of this inven tion, referenceis made to United States Patent No. 2,5l7,989-Dodge-assigned to the sameassignee as that 'of the present invention wherein a completedescription of the basket shift mechanism for upper and lower casecontrol of an IBM typewriter is shown.

The aforementioned United States patent describes in detail the shiftmechanism shown in Fig. 3 of the subject application, and accordingly,it is felt that a brief statement regarding its operation will sufiicefor the purpose of this description. Specifically, a power roll 2 ismotor driven in a clockwise direction as viewed in Fig. 3, while a shiftcam unit 4 is pivotally supported in the typewriter response todepression of the shift lever 6, and particularly through the push oflink 7, shift cam 8 is moved.

into operative engagement with the power roll 2 for one half revolutionthereby causing the cam unit 4 to .be driven about its bearing support10 to exert a pull on link 12 that rocks lever 14 clockwise about itspivot 16.

Conjointly, with the actuation of shift cam 8 through the depression ofthe shift lever 6, an extension 18 of the shift lever 6, whichincidentally, is pivotably supported by stud 20, lifts the trip link 22thereby conditioning a yoke 24 so that one of its legs 26 is positionedfor engagement with stud 28 extending laterally from a shift plate 30which, in turn, is pivotally supported on cross shaft 32.

concomitantly, with the conditioning of yoke 24, the shift link 12, inrocking lever 14 clockwise about pivot 16, causes yoke leg 26 to push onstud 28 fl'lereby rocking shift plate 30 counterclockwise about itssupporting cross shaft 32. Through this operation, the connecting arm 34from engagement with the shift cam 8 which then makes another halfrevolution, again exerting a pull on the shift link 12 to rock lever 14clockwise about pivot 16; but conjointly, with the actuation of theshift cam, the trip link 22 will have positioned the yoke 24 so that itsleg 40 will engage a stud 42 whereby, in response to the rocking of thelever 14, shift plate 30 will be rotated clockwise about cross shaft 32thereby restoring basket 38 to its normal or lower case position.

As heretofore mentioned, a complete description of this shift operationis given in the United States Patent 2,517,989; but for the purposes oflaying the ground work for the subject invention, it seems sufficient tosay that in response to depression of the shift key lever 6, the shiftplate 30 is rotated counterclockwise about shaft 32 while upon releaseof the shift key lever 6, the shift plate 30 is rocked clockwise fromits upper case position back to the lower case position shown in Fig. 3.Obviously, suitable stops are provided to limit the degree of rockingmovement of the shift plate 30 and furthermore toggle springs 44 and 46as described in Patent 2,517,989 are provided to accurately position theshift mechanism at either limit of its motion- In accordance with theteachings of this invention, shift plate 30 is provided with an arm 50carrying a stud 52 which arm is rocked with plate 30 from the lower toupper case position and return. An actuating link 54 is positioned tointerconnect the stud 52and a stud 56 carried by a gear sector 58 whichis pivoted on stub shaft 60 carried by the typewriter frame. The gearsector 58 is mounted for engagement with an impression control mechanism62, which, in turn, is supported for engagement with the typewriterletter cams, hereinafter described, by means of shaft 64 bushed in thetypewriter frame.

Before describing in detail the structure of the impression controlmechanism 62, reference is made to United States Patent2,506,444Dodge-assigned to the same assignee as that of the presentinvention for a reference to the type bar drive mechanism and the methodof controlling the extent of its power driven lift through thepositioning of an adjustable stop in the path of the tail .of a lettercam. By changing the axial position of the adjustable stop-as shown inFig. 2 of the subject Patent 2,5'06,444the type bar print force can becontrolled, and sincea similar adjustable stop is provided for each ofthe type bar drive mechanisms, a uniform pressure per unit area can beprovided for either (but not both) the lower or upper case setting ofeach type bar.

In accordance with the teachings of this invention, to

' provide an individually adjustable impression control earn stop forupper and lower case control of each of the letter cams, and moreparticularly to provide such an upper and lower case control for twoentirely different typing conditions (or condition changes), theimpression control member 62, as shown more completely in Fig. 6, isprovided with four circumferentially spaced rows of adjustable stopswhich, in the illustrated embodiment, are set screws. One row of screwsis utilized for the lower case while an adjacent row is used for theupper case position for any predetermined printing condition of thetypewriter. Specifically (Fig. 6), each of four radially extendingcircumferentially spaced bosses 70 is provided with spaced, 'tappedholes along its entire length so that there will be one set screw foreach of the forty-two letter cams-one for each of the type bars usuallyprovided on the standard typewriter. An axial slit 71 in each of thebosses 70 houses a resilient strip 72 which has been compressed into itsrespective slit. The latter then has its outside edges rolled over tomaintain a pressure on the adjusting screws to act as a locking devicefor each of the set screws passing through it. It should be stressedthat the impression control member can be considered as being divided byparallel planes passing perpendicularly through its axis into fortytwoelements, each one of which has four set screws positioned 90 apartwhereby a set screw (or adjustable stop) is provided for upper and lowercase impression control for each of two different typewriter operatingconditions. In this manner, an impression control mechanism is providedwhich will meet the objects of this invention when employed inconjunction with a positioning device which will lock the selected rowof set screws in impression control position. I

Positioning device In order to position the proper rows of set screwsfor operative engagement with the tails of the letter cams, shaft 64 isprovided (Fig. 3) with a gear 74 in mesh with the teeth of the sector58. With this arrangement of parts, then in response to depression ofthe shift key lever 6, which as heretofore described causes thecounterclockwise rocking of shift plate 30 on cross shaft 32, armthrough its stud 52 pushes on actuating link 54 causing it to exert aforce at stud 56 which rocks sector 58 counterclockwise about its pivot60 thereby rotating the impression control member 62 clockwise 90 aboutits axis to position a different row of set screws for operativeengagement with the tails of the letter cams.

Obviously, it is necessary that the rows of set screws be rotated anexact amount for engagement with the tails of the letter cams, and toaccomplish this result, a detent mechanism is provided as shown in Figs.2, 4 and 5. Specifically, a bushing 80 (Fig. 2) is mounted in the rightside 82 of the typewriter frame both to support the impression controlshaft 64, and also to mount a detent mechanism to properly position theselected row of set screws. A washer-like element 84 is mounted on thebushing 80 for movement transverse to the axis of and in juxtapositionwith the bushing for a purpose hereinafter described. The washer element84 preferably is made of resilient material, or one of the polyesters,in order to reduce the noise of the detent. The washer element has adiametrical groove which provides diametrically opposite radial slots86, 88 (Fig. 4) each having one shoulder as, for example, the shoulder90 (Fig. 2) which is cut away to provide a recessed portion 92 throughsubstantially 180 of one face of the washer. A detent carry 94 isoperatively connected to the shaft 64 in a manner hereinafter describedand carries two pins 96, 98 (Fig. 4) which are so positioned that theyrock 90 from their normal to their detent position. For example, if thedetent carry 94 is rocked from the position shown in Fig. 4 so that thepin 96 engages the radial slot 88, one row of set screws will have beenmoved 90, so that it is in operative relation with the tails of theletter cams. With this arrangement then, the depression of shift keylever 6 causes the sector 58 to be rotated thereby rotating theimpression control member 62, so that either pin 96 or 98 is positionedin its cooperative radial slot 86 or 88 thereby insuring the properlocation of a row of set screws for engagement with the tails of theletter cams.

It has been pointed out in the introductory paragraph of thisspecification, that it is necessary to provide a group impressioncontrol for typewriters whereby for any one setting whether it be upperor lower case position-the range of impression can be variedconsiderably to regulate the color density of a printed character. Inaccordance with the teachings of this invention, and in order to providethe required group control, the bushing mounted in the frame member 82is provided with a transverse radial slot 100 (Fig. 4) while the face ofthe washer I 84 in contact with the bushing 80 has a transverse tongue101 engageable with the slot 100 whereby the washer element 84 can bedisplaced transversely of the axis of the bushing 80 with the tongue 101riding in the slot 100.

Substantially, the whole length of shaft 64 within the axial limitsofthe central bore of the impression control member is provided wtih aneccentric 102 (Fig. 2) and when shaft 64 is rotated by means of a groupcontrol lever 104 rigidly secured to shaft 64, the motion of theeccentric 102 causes the impression control member 62 It has beenmentioned that one of the objects of this invention is to provide a dualcondition typewriter whereby the improved impression control may be usedwith either of two.sets of typewriter operating conditions,

and, in accordance with the teachings of this invention,.

two rows of impression control set screws are provided for eachcondition. In order to selectively position the desired pair of rows foroperative engagement with the tails of the letter cams, a conditionchange mechanism is provided which comprises (note Fig. 1) a manuallyoperated condition switch or button 106, mounted on an arm 108 rigidlysecured to a .cross shaft 110 which, as shown in Fig. 2, is pivotallysupported in the typewriter frame by means of bushings 112, 114.Depending from the rod 110 and rigidly secured thereto, is a conditionarm 116 which is rocked in response to a push on the button 106 fromright to left in the direction of the arrow shown .in Fig. 1. Thecondition arm 116 carries a condition link 118 which is pivotallyconnected to a condition yoke 120. Yoke 120 which is rotatably supportedon impression control member 62 carries a pawl 122 which is pivotallysupported by the pin 124 and normally held out of engagement with theteeth of a ratchet 128 by means of a spring 126. With this structure,the ratchet 128 which is secured to impression control member 62normally can rock under the pawl 122. However, upon movement of thecondition switch in the direction of thearrow (Fig. 1) the depending arm116 is rocked clockwise as shown in Fig. 1, thereby lifting the tail 130of'pawl 122 thus engaging the pawl with the teeth of ratchet 128 andsimultaneously, the thrust of link 118 caused by the clockwise rockingof depending arm 116 causes yoke 120 to be moved counterclockwisethereby rotating ratchet 128 counterclockwise. The ultimate objective ofthe operation of this mechanism is to produce 180" of rotation on theratchet 128 and hence impression control member 62 thereby conditioningthe latter for operative engagement with the letter cams under a secondset of typing conditions. It should be noted that depending arm 116ismaintained normally at its counterclockwise limit by the spring 132which interconnects the depending arm 116 and a stud 134 extendinglaterally from the typewriter frame 82.

With reference nowto Figs. 1 and 2, detent carry 94 is connected toimpression control member 62 through a second or condition detentmechanism 136 which comprises a condition detent carry 138 that ismounted for axially slidable movement on the shaft 140 which carriesratchet 128. The shaft 140, incidentally, along with impression controlmember 62 to which it is secured, is freely rotatable about theimpression control shaft 64 and can be rocked by the control gear 74through the condition detent 136. When the spring 142 normally positionsthe detent carry 138 so that its pins 144, 146, engage the radiallyopposite grooves 148 (Fig. carried by one end of the detent carry 94,then the impression control member 62 may be rotated through 90 inresponse to the operation of the shift control mechanism.

Through the operation of the condition control button 106 (Fig. l), thepins 144 and 146 can be displaced 180 relative to their position so thatthe second pair of rows of setscrews are located for operativeengagement with the tails of the letter cams. In order to effect this180 shift, the rocking of the depending arm 116 in response to the pushon the condition switch button 106 brings the pawl 122 into engagementwith ratchet 128 to rotate the latter and shaft 140 counterclockwise asviewed in Fig.1. This counterclockwise rotation breaks the pins 144, 146out of the radial grooves 148, by permitting the spring 142 to becompressed thereby allowing the condition detent carrier 138 to be slidalong shaft axially to the left, as viewed in Fig. 2.v Successive pusheson condition switch button 106 cause the rotation of ratchet 128 a fewteeth at'a time until the pins 144, 146 are displaced from the positionshown in Fig. l whereupon the pins drop into radially extending grooves148, thereby selectively conditioning impression control member for asecond set of typing conditions.

While this mechanism has been described for a typewriter having only twosets of conditions, it is readily apparent that by providing impressioncontrol member 62 with six rows of set screws, the typewriter, ifnecessary, could be constructed to act under three different sets ofconditions; or if only two rows are provided, then the impressioncontrol mechanism would condition the typewriter for upper and lowercase control as may be required for any one set of conditions.

While there have been shown and described and pointed out thefundamental novel features of the invention as applied to a preferredembodiment, it will be understood that various omissions andsubstitutions and changes in the form and details of the deviceillustrated and in its operation may be made by those skilled in the artwithout departing from the spirit of the invention. It is the intention,therefore, to be limited only as indicated by the scope of the followingclaims.

What is claimed is:

1. In a typewriter having a plurality of type bars each having aplurality of character positions, a plurality of rockable membersselectively operable to drive an associated type bar to printingposition, and a shift mechanism for selecting which character positionon a type bar is to be printed, an impression control mechanismcomprising a stop member having a plurality of rows of adjustable stopswith one row being allocated for each character position on said typebars, means mounting said stop member in said typewriter for rockingmovement to selectively position a predetermined row of stops inoperating position for engagement with said rockable members therebyregulating the driving force imparted to a type bar by a rockablemember, and link means interconnecting said stop member with said shiftmechanism to position the allocated row of. stops in said engagingposition in response to the selective operation of said shift mechanism.

2. In a typewriter having a plurality of multi-character type bars, ashift mechanism for selecting which character of a multi-character typebar is to be printed, and a plurality of rockable members selectivelyoperable to drive an associated type bar to printing position, animpression control mechanism comprising an axially elongated memberhaving a set of circumferentially spaced axial rows of adjustable stopswith one row allocated for each character position on said type bars,means mounting said elongated member in said typewriter for rockingmovement to selectively position a predetermined row of stops foroperative engagement with said rockable members, and link meansinterconnecting said shift mechanism with said elongated member forrocking the latter to position a predetermined one of said rows forengagement with said rockable members in response to a selectiveoperation of said shift mechanism.

3. In a typewriter having a plurality of two-character type bars, ashift mechanism for selecting which character of a two-character typebar is to be printed, and a plurality of rockable members selectivelyoperable to drive an associated type bar to printing position, animpression control mechanism comprising an axially elongated memberhaving a plurality of pairs of circumferentially spaced axial rows ofadjustable stops, means mounting said elongated member in saidtypewriter for rocking movement to. selectively position either row of apair of rows of stops for operative engagement with said rockablemembers, link means interconnecting said shift mechanism with saidelongated member for rocking the latter to move either row of a pairinto engagement with said rockable members in response to selectiveoperation of said shift mechanism, and condition change means for movinga selected pair of said rows of stops into position to be operated inresponse to the selective operation of said shift mechanism.

4. In a typewriter having a plurality of multi-character type bars, ashift mechanism for selecting which character of a multi-character typebar is to be printed, and a plurality of rockable members selectivelyoperable to drive an associated type bar to printing position, animpression control mechanism comprising an axially elongated mem berhaving a plurality of sets of circumferentially spaced axial rows ofadjustable stops, means mounting said elongated member in saidtypewriter for rocking movement to selectively position one row of a setfor operative engagement with said rockable members, linking meansinterconnecting said shift mechanism with said elongated member forrocking the latter to move one row of a set into engagement with saidrockable members in response to selective operation of said shiftmechanism, and a condition change means for moving a set of said rows ofstops into position to be operated in response to the selectiveoperation of said shift mechanism, said condition change meanscomprising a ratchet wheel secured to said elongated member, a pawlengageable with said ratchet wheel to rotate the latter, and crank meansfor moving said pawl into engagement with said ratchet wheel to efiectthe rotation of the latter to position a set of rows for operativeengagement with said rockable members.

5. In a typewriter having a plurality of multi-character type bars, ashift mechanism for selecting which character of a multi-character typebar is to be printed, and a plurality of rockable members selectivelyoperable to drive an associated type bar to printing position, animpression control mechanism comprising an axially elongated memberhaving a set of circumferentially spaced axial rows of adjustable stopswith one row allocated for each character position on said type bars,means mounting said elongated member in said typewriter for rockingmovement to selectively position a predetermined row of stops foroperative engagement with said rockable members, link meansinterconnecting said shift mechanism with said elongated member forrocking the latter to a selected position in response to a selectiveoperation of said shift mechanism, and a cam operated group controldevice for displacing the axis of said elongated member, to vary therelative point of engagement between each of said adjustable stops andits respective rockable member thereby varying the imprint force of eachtype bar.

. 6. In a typewriter having a plurality of multi-character type bars, ashift mechanism for selecting which character of a multi-character typebar is to be printed, and'a plurality of rockable members selectivelyoperable to drive an associated type bar to printing position, animpression control mechanism comprising an elongated cylindrical barhaving circumferentially spaced axially extending bosses mountedthereon, a row of tapped holes in each of said bosses, with the axes ofcorresponding tapped holes in each of said bosses lying in the sameplane, an adjustable set screw positioned in 'each of said tapped holes,means mounting said elongated member in said typewriter for rockingmovement to selectively position a predetermined row of set screws foroperative engagement with said rockable members, thereby regulating thedriving force imparted to a type bar by its associated rockable member,and link means interconnecting said shift mechanism with said elongatedmember to effect said selective movement of the latter in response tooperation of said shift mechanism.

7. In a typewriter having a plurality of multi-character type bars, ashift mechanism for selecting which character of a multi-character typebar is to be printed, and a plurality of rockable members selectivelyoperable to drive an associated type bar to printing position, animpression control mechanism comprising an elongated cylindrical bar,four circumferentially spaced axially extending bosses mounted thereon,a plurality of tapped holes in each of said bosses with the axes ofcorresponding tapped holes in each of said bosses lying in a commonplane, an adjustable stop member in each of said tapped holes, meansmounting said elongated member in said typewriter for rocking movementto selectively position a predetermined row of said stop members foroperative engagement with said rockable members, linking meansinterconnecting said shift mechanism with said elongated member forrocking the latter in response to selective operation of said shiftmechanism, and a condition change means for moving a predetermined pairof said rows of stop members into position to be operated in response tothe selective operation of said shift mechanism, each of said bosses onsaid elongated member having a resilient strip wedged therein to act asa locking device for said adjustable stop members passing through saidtapped holes.

References Cited in the file of this patent UNITED STATES PATENTS

